BUG: Frozen & Stuck Sims

Problem 
My Sim is frozen and doens't move anymore

Cause
Frozen Sims are pretty common since LN came out and their source is unclear which makes this problem very hard to pinpoint a cause or even find a solution for this. I'm trying to list a few anyway.

• Incompatible Mods/CC--> Could be a cause. Remove them all to make sure, it's not the cause
• A stuck sim causes another sim that wants to interact with him to be frozen as well. 
• Sim is stuck in an object (especially bed)
• Bridgeport has two places in the hill behind the hospital where sims can go but because it's very hard to get there, Sims try to go there indefinitely or never get back out. 
• ...

Solutions
To make your sim move again, you will need to reset him. Sometimes this can actually make it worse and make your sim invisible.

Mods that might help with the issue

• ErrorTrap might be able to save the town by cleaning up some stuff and loose ends
• MasterController has the option to reset the whole town. It not only resets all sims but also all objects.
• Overwatch does some nightly cleanups that might help with the issue

Further Reading

• Game Help:Intermittent Freezes